Examinations
Examinations
Vitamin A is essential for normal vision, immune function, embryonic development, skin integrity, bone formation, and cell growth. It plays a crucial role in forming eye photoreceptors, maintaining the structure of mucous membranes, and supporting skin health.
Vitamin A deficiency can cause night blindness (nyctalopia), eye damage, and in severe cases, permanent blindness. On the other hand, excessive intake of vitamin A can be toxic, potentially leading to birth defects, liver damage, and bone abnormalities.
Sources of Vitamin A
- Animal sources: Found in its active form as retinol in meat, especially liver.
- Plant sources: Found as carotenoids (provitamin A), which are converted into retinol in the liver.
Vitamin A is fat-soluble and stored in the liver and fat tissues. The body regulates its levels by adjusting absorption from food and releasing it when needed.
Who is at Risk of Vitamin A Deficiency?
- Malnourished individuals
- People with absorption disorders (Celiac disease, Crohn’s disease, cystic fibrosis, chronic pancreatitis)
- Elderly individuals
- Chronic alcoholics
- Patients with liver diseases
Vitamin A Toxicity
Toxicity is mainly caused by excessive intake of supplements, but in rare cases, it may result from consuming foods with extremely high vitamin A levels, such as animal liver.
- Sample Type: Venous blood
- Fasting Required: 8 hours (only water allowed)
- After a light meal: Wait at least 4 hours before the test
To Diagnose Vitamin A Deficiency (linked to malabsorption and poor nutrition):
- Night blindness
- Dry eyes, skin, and hair
- Corneal ulcers or damage
- Thin, rough skin
- Gray-green patches on the skin
- Chronic infections
- Anemia
To Monitor Vitamin A Absorption in Conditions Such As:
- Celiac disease
- Spastic colitis
- Crohn’s disease
To Detect Vitamin A Toxicity (excess intake or supplement overdose):
- Headache
- Nausea and vomiting
- Blurred or double vision (diplopia)
- Fatigue, dizziness, irritability
- Muscle, bone, and joint pain
- Rapid weight loss
- Hair loss
- Dry mucous membranes, cracked lips, glossitis (tongue inflammation)
- Liver dysfunction
Normal Range
- A normal result means there is sufficient vitamin A in the bloodstream.
- However, this test does not measure stored vitamin A levels in the body. The blood concentration remains stable until liver reserves are significantly depleted.
Low Vitamin A Levels
Indicates severe depletion of stored vitamin A and suggests a deficiency.
High Vitamin A Levels
- Suggests that the body's storage capacity is saturated, leading to excess vitamin A circulating in the blood.
- Prolonged elevation may cause toxic effects, accumulating in tissues.
This test helps evaluate vitamin A levels but does not measure total body reserves. If a deficiency or toxicity is suspected, clinical assessment and dietary evaluation are essential.